i learned what now know to this day from random articles on google :) now i am really good at C#, XNA , C++, QBASIc, Vb.Net :) they are really usefull ^^ i develop 2d games now :) and i have knowledge of ASP.NET and PHP, Perl... HTML...

Jquery has more user base,Coffe script is easier to learn incase You know python or ruby,It is inspired syntax and philosophy from both.It save LOC and Rails 3.1 javascript library coffescript will be supported.
Advantages:
Readability: clearly it resolved most of javascript syntax problems
Verbosity: I gained 14% line, 22% words, 14% characters
Disadvantages:
Added another compilation step to see how my code behave on the website.
I had to launch some script to generate on change every of my javascript file
I have to learn another Ruby-like language,
meta-programming become a poor experience,
I must convince people working with me to:
install node.js, npm and CoffeeScript,
remember to launch a script at each code session,
learn and use another ruby-like language
I want programmers to be productive ,that is the reason.I am learning coffee script and in future more people will be using and coffe script is one of the most watched repo in github.